FWP:
SETS == A,B; GENERATORS; VARNAH
JALVAH: {7,4}
MIRROR: {8,3}
For background see S. R. Faruqi's choices. For more on Ghalib's unpublished verses, see the discussion in {4,8x}.
The first line gives us a very general rule about passion and the manifestation of glory/appearance; the second line tells us that 'otherwise' the expansiveness of a mirror chamber-- well, it's (idiomatically) 'known', meaning known to be nothing; for more on this usage see {4,3}. For more on the nature of mirror-chambers, see {10,5}.
But it's that 'otherwise' that really fuels the verse. First of all, it can be grammatically either in the present tense ('is') or in the contrafactual ('would have been'). Obviously, to say that the mirror-chamber's expanse 'is' nothing, or that it 'would have been' nothing, makes a considerable difference.
But then the further question arises: what does the 'otherwise' apply to? Presumably to something in the first line-- but what exactly? Are we to envision a contrasted situation in which the spirit/capacity is (or might have been) lacking? Or the passion? Or the glory/appearance? Or the scattering?
And then, it's also unclear whose passion is at issue-- the mirror's, or the mirror-chamber's (as Gyan Chand explains), or that of the lover himself (human passion itself might be behind all divine manifestations in the world; or human passion might be the inducement that causes God to display glory/appearance). And is the 'mirror-chamber' the world itself, and the glory/appearance the light that causes it to sparkle? Or is it just a mirror-chamber, invoked as a metaphor?
In short, with all these mix-and-match permutations, this is another open-ended 'put it together yourself' verse.
Zamin:
He says, 'For heaven's sake, in a tiny mirror how can there be enough breadth/scope-- but this is its lofty spirit/capacity, that as far as the horizon, everything is comprised within it!' Thus it's become clear that for the glory-scattering of beauty there is no special container-- however much spirit/capacity will be in the lover's heart, just that much will beauty do glory-scattering upon him. That is, however much ability to receive mystic knowledge there will be in the heart, that much will Absolute Beauty do glory-scattering upon him.
== Zamin, p. 221